Hii Manisha !

Yes, practically speaking you need to prepare the entire class 11 and 12 syllabus because the exam questions are framed from these topics. But to be honest AIIMs has not provided any detailed chapterwise syllabus for nursing. They expect you to study from the standard NCERT / board curriculum of class 11 and 12.

Therefore, keep in mind that AIIMS BSc nursing entrance exam does not release any separate official syllabus. Instead the exam is entirely based on the class 11th and 12th science curriculum which includes physics, chemistry and biology along with a small portion of general knowledge.